One of the steno machines I have has a light-colored carrying case. I noticed how dirty the case can potentially get. My schoolmates who have had the machine longer than I have, have cases that have become a bit weathered looking. If you carry the case hanging from your shouldered, it could also easily become stained from clothes dye when the case constantly rubs against your clothing.
Since this machine is the one that I am most likely to carry when I am not going to work, but still want to have a machine with me to practice at opportune times, I want to be able to keep the case as clean as possible.